1. Field of the Invention
With reference to the classification of art as established in and by the U.S. Patent Office, this invention is believed to be found in the General Class entitled, "Dentistry" (Class 433) and more particularly in the subclass entitled, "Orthodontics-tool-plier type" (subclass 4).
2. Description of the Prior Art
In the practice of orthodontics, the use of wires to retain, manipulate and adjust teeth into a desired alignment is an established procedure. In particular, clips and the like are cemented to teeth and wires are fed into these clips and attached in a desired manner to cause the teeth to be adjusted to a desired position or condition. In the forming and attaching of these wires, a small surplus of wire at one or both ends is customarily provided as a practical matter. After the completion of the installation of the wire in the mouth, the dentist trims or cuts the surplus end or ends of the wire from the retaining configuration. The wire customarily used in orthodontics is a very high tensile alloy wire usually semi-hard so that in the cutting of this wire by diagional cutters or nippers the short surplus or unattached end has a tendency to fly. This flying end portion may cause injury to the patient unless the orthodontist takes careful steps to catch or trap it.
In the use of wires in orthodontics, it is of particular note that the cutting of the wire should produce no misalignment or dislodgement of the wire from its installed position. It is also important that the surplus end of the wire, when cut from the installed wire, should not fly into the patient's mouth tissues or throat or in any other manner be a danger to the patient. In the embodiments of the wire cutting tool of this invention said tool jaws are disposed to provide a shear cut and retaining of the severed end. The hardened wire, such as used in the formation of the orthodontic bridge, and the trimmed or cut portion of the wire is gripped and retained by a shelf portion and a leaf spring portion. When the tool is moved to shear cut and to a closed condition it is removed from the mouth and the trimmed portion of the wire is released and discarded from the then opened tool.
A shear-type cut and hold pliers shown in U.S. Pat. No. 3,555,677 as issued Jan. 19, 1971 is of limited utility to dentists because such pliers do not accommodate different sized wires. This is because the gripping faces are positioned and dimensioned with respect to the cutting edges on the blades so as to enable the distal end of the wire to be gripped just as the cut is being completed. The use of larger diameter wire than that for which the cutter is designed results in the wire not being cut through. This is because the gripping jaws engage the wire before the cutting edges come together the requisite amount to achieve and complete the cut. On the other hand, if a wire has a diameter which is less than that for which the cutter is designed, the distal end of the wire flies from the pliers before the gripping jaws can engage it.
In order to have a successful shearing tool, the shearing blades must be mounted so that they slide past each other. Thus, it is essential in such a tool that the means which support the movement of the shearing blades as they pass each other be carefully and accurately made since relative movement of the shearing blades will interfere with the cutting action.
In the wire cutting tool of this invention two patents are particularly noted. U.S. Pat. No. 3,555,677 as issued to Cusato on Jan. 19, 1971 shows a shear cutting tool particularly for wires fifteen thousandths of an inch or less. U.S. Pat. No. 3,922,781 of Dec. 2, 1975 to Tippy shows a diagional cutter in which a wire is disposed to be carried adjacent to the cutting edges of the compression-type cutter and this wire is disposed to grab, engage and retain the small and loose end of the cut wire.
In the course of a pre-Ex search diagional wire cutters were found and among those diagional cutters with holding attachments were U.S. Pat. No. 3,908,268 to Brown as issued on Sept. 30, 1975; U.S. Pat. No. 3,722,093 to Kaupman as issued on Mar. 27, 1973; U.S. Pat. No. 3,740,844 as issued on June 26, 1973 to Rubin; U.S. Pat. No. 3,763,560 as issued to Makkay et al., on Oct. 9, 1973; U.S. Pat. No. 3,777,398 as issued on Dec. 11, 1973 to Routh, Jr.; U.S. Pat. No. 3,842,500 as issued on Oct. 22, 1974 to Cassel and U.S. Pat. No. 4,023,270 as issued May 17, 1977 to Hellerman et al. These all pertain to compression cutting in which the jaws are sharpened and mate to compression cut the wire. Adjacent one or both of the jaws are resilient means for retaining the cut wire. The present invention does not anticipate cutting of the wire by diagional-type cutters. This is commonly called a diagional or compression cut and is not anticipated in the present invention.